Question

Which of the following statements are true?
I. Each white blood cell contains millions of hemoglobin molecules.
II. In a sample of blood, there are more red blood cells than white blood cells.
III. HIV destroys red blood cells.
IV. All blood cells come from one pool of stem cells.
II and IV only
I and IV only
II and III only
I, III, and IV only
I, II, and IV only

Answer 1

II and IV only

Explanation: Hemoglobin is in red blood cells, not white blood cells (so I false). Red blood cells are far more numerous than white blood cells (II true). HIV infects and destroys CD4+ T lymphocytes (white blood cells), not red blood cells (III false). All blood cells arise from hematopoietic stem cells in the bone marrow (IV true).